The Doctor's proximity caused the drums to swell in the Master's head till he could barely think. Strange that while the other Doctor who wasn't his had calmed him, silenced the drums, through simply wanting him and showing it, this Doctor was having completely the opposite effect.
Even with all the flirting and using his name... there was a game going on here. This Doctor was hot and entertaining and - yeah - thrilling, but the Master didn't trust him one little tiny bit.
He leaned across the bare inches separating them now and slid his jaw alongside the Doctor's so he could murmur in his ear, "Three years since my 'death' and you really haven't been out there scouring the heavens for me? Really?"